Valhalla

"To win this battle you must control a majority of the hosts for as long as possible. To take control of o host, write any value to its #CTRL register. Reading from a #CTRL register will tell you if you (1) or your opponent (-1) controls the host. Gain one point every cycle you control more hosts than your opponent. Lose one point every time your EXAs executes a KILL instruction."

Your NPC opponent, #plastered, uses only one EXA which travels around the network setting control bytes. You should be able to easily defeat them by using multiple EXAs.